The Gravity Field and Steady-State Ocean Circulation Explorer (Goce) observatory has produced the most detailed map of ocean currents ever created, and that project is yielding its first scientific discoveries.
The European Space Agency (ESA) manages the orbiting observatory, which also produced the most accurate maps yet developed of the gravitational field of the Earth.
The Goce spacecraft was launched into orbit in March 2009, completing 27,000 orbits of the Earth before re-entering the atmosphere on November 11, 2013.
Gravitational mapping of the Earth by Goce allows researchers the ability to measure the density of features beneath the surface of land or the ocean, providing information about geological compositions in various regions.
The new gravitational map of our home planet was developed from 800 million observations, each with a resolution of less than 44 miles. These observations were merged together, in order to better improve the accuracy of the map. After data was compiled, one variation of the chart called a geoid, used to measure the height of land and water, achieved an accuracy of 0.4 inches.
"This resulted in a unique model of the 'geoid', which is the surface of equal gravitational potential defined by the gravity field - crucial for deriving accurate measurements of ocean circulation and sea-level change, both of which are affected by climate change," European Space Agency officials wrote on a web page for the mission.
In short, a geoid describes the shape oceans would take if they were affect by just gravity, without water currents or wind to shape their behavior. By studying the difference between these maps and observed movement, scientists can find where water is "built up," leading to ocean currents.
Gravitational mapping of the Earth allows researchers to study the speed at which ocean currents travel, creating the most-detailed chart of its kind ever produced. Melting ice sheets and rising sea levels may also be monitored using detailed maps of the planet's gravitational field.
The great detail in the data allowed scientists "to create the first global high-resolution map of the boundary between Earth's crust and mantle - called the Moho - and to detect sound waves from the massive earthquake that hit Japan on 11 March 2011," Goce engineers stated.
The Goce satellite was launched into an orbit much lower then other Earth-orbiting observatories, skimming the upper atmosphere, just 158 miles above the planet. The vehicle kept itself aloft using an ion propulsion system, providing enough thrust to maintain a stable orbit. After supplies of propellant ran out, atmospheric drag built up, until the observatory fell from the sky.
Development of the new map using data obtained by Goce was detailed in the journal Geophysical Research Letters.
